   atom. validate-fn must be nil or a side-effect-free fn of one
   argument, which will be passed the intended new state on any state
   change. If the new state is unacceptable, the validate-fn should
-  return false or throw an exception."
+  return false or throw an Error."
   ([x] (Atom. x nil nil nil))
   ([x & {:keys [meta validator]}] (Atom. x meta validator nil)))
 

  (-deref o))

(defn set-validator!
  "Sets the validator-fn for a var/ref/agent/atom. validator-fn must be nil or a
  side-effect-free fn of one argument, which will be passed the intended
  new state on any state change. If the new state is unacceptable, the
  validator-fn should return false or throw an exception. If the current state (root
  value if var) is not acceptable to the new validator, an exception
  will be thrown and the validator will not be changed."
  [iref val]
  (set! (.validator iref) val))


  fn of 4 args: a key, the reference, its old-state, its
  new-state. Whenever the reference's state might have been changed,
  any registered watches will have their functions called. The watch
  fn will be called synchronously. Note that an atom's state
  may have changed again prior to the fn call, so use old/new-state
  rather than derefing the reference. Keys must be unique per
  reference, and can be used to remove the watch with remove-watch,
  but are otherwise considered opaque by the watch mechanism."
  [iref key f]
